0005433: New ARM backend

(0006497)
meurer (developer)
2011-12-22 11:43

Attached a new patch, which does no longer includes the config.guess/config.sub upgrade (see PR#5439 for that), therefore only half the size of the previous patch.

(0006780)
xleroy (administrator)
2012-01-23 15:48

I have a concern about Proc.destroyed_at_oper, case Iop(Iextcall(_, true)): the result should really be all_phys_regs as in the original code. Indeed, an allocating extcall can raise a Caml exception, which will not reload any of the callee-save registers. Also, such an extcall can trigger a GC, and if GC roots are stored in callee-save regs across the Iextcall, the GC assumes that these callee-save regs have been saved in memory in a location pointed to by caml_gc_regs (cf. caml_call_gc in asmrun/<proc>.S). For both reasons, all Caml values live across a Iextcall(_, true) must be stack-allocated, and this is achieved by saying that the Iextcall destroys all registers.

(0006787)
meurer (developer)
2012-01-23 19:44

Ok, makes sense. It's fixed in ocaml-arm:

https://github.com/bmeurer/ocaml-arm/commit/7658da046c3fe4066c6753691e9131d73b2bde4a [^]

(0006877)
meurer (developer)
2012-02-04 11:18

I just merged the latest commit ec5b444c7f of my development repository at https://github.com/bmeurer/ocaml-arm/tree/ec5b444c7f [^] into trunk with revision 12124.

Issue History
Date Modified	Username	Field	Change
2011-12-18 14:13	meurer	New Issue
2011-12-18 14:13	meurer	File Added: ocaml-arm-3.12.1+20111218.diff.bz2
2011-12-22 11:41	meurer	File Added: ocaml-arm-3.12.1+20111222.diff.bz2
2011-12-22 11:43	meurer	Note Added: 0006497
2012-01-17 11:04	lefessan	Relationship added	has duplicate 0005404
2012-01-23 15:48	xleroy	Note Added: 0006780
2012-01-23 15:48	xleroy	Status	new => feedback
2012-01-23 19:44	meurer	Note Added: 0006787
2012-01-23 19:44	meurer	Status	feedback => new
2012-01-31 08:49	xleroy	Assigned To	=> meurer
2012-01-31 08:49	xleroy	Status	new => assigned
2012-02-04 11:18	meurer	Note Added: 0006877
2012-02-04 11:19	meurer	Status	assigned => resolved
2012-02-04 11:19	meurer	Resolution	open => fixed
2013-05-08 15:26	meurer	Status	resolved => closed
2013-05-08 15:26	meurer	Fixed in Version	=> 4.00.0+beta2/+rc1

Notes
(0006497) meurer (developer) 2011-12-22 11:43	Attached a new patch, which does no longer includes the config.guess/config.sub upgrade (see PR#5439 for that), therefore only half the size of the previous patch.

(0006780) xleroy (administrator) 2012-01-23 15:48	I have a concern about Proc.destroyed_at_oper, case Iop(Iextcall(_, true)): the result should really be all_phys_regs as in the original code. Indeed, an allocating extcall can raise a Caml exception, which will not reload any of the callee-save registers. Also, such an extcall can trigger a GC, and if GC roots are stored in callee-save regs across the Iextcall, the GC assumes that these callee-save regs have been saved in memory in a location pointed to by caml_gc_regs (cf. caml_call_gc in asmrun/<proc>.S). For both reasons, all Caml values live across a Iextcall(_, true) must be stack-allocated, and this is achieved by saying that the Iextcall destroys all registers.

(0006787) meurer (developer) 2012-01-23 19:44	Ok, makes sense. It's fixed in ocaml-arm: https://github.com/bmeurer/ocaml-arm/commit/7658da046c3fe4066c6753691e9131d73b2bde4a [^]

(0006877) meurer (developer) 2012-02-04 11:18	I just merged the latest commit ec5b444c7f of my development repository at https://github.com/bmeurer/ocaml-arm/tree/ec5b444c7f [^] into trunk with revision 12124.